6.(6) The manufacture for, transfer to, or possession by the United States or a department or agency of the United States or a State or a department, agency, or political subdivision of a State, or a transfer to or possession by a law enforcement officer employed by such an entity for purposes of law enforcement;

7.(7) The transfer to a licensee under title I of the Atomic Energy Act of 1954 (42 U.S.C. 2011 et seq.) for purposes of establishing and maintaining an on-site physical protection system and security organization required by Federal law, or possession by an employee or contractor of such licensee on-site for such purposes or off-site for purposes of licensee-authorized training or transportation of nuclear materials;

8.(8) The possession, by an individual who is retired from service with a law enforcement agency and is not otherwise prohibited from receiving a firearm, of a semiautomatic assault weapon transferred to the individual by the agency upon such retirement;

1.(1) Contracts between the manufacturer and dealers stating that the weapons may only be sold to law enforcement agencies, law enforcement officers, or other purchasers specified in paragraph (b) of this section;

2.(2) Copies of purchase orders submitted to the manufacturer or dealer by law enforcement agencies or other purchasers specified in paragraph (b) of this section;

4.(4) Letters from dealers to the manufacturer stating that sales will only be made to law enforcement agencies, law enforcement officers, or other purchasers specified in paragraph (b) of this section; and

5.(5) Letters from law enforcement officers purchasing in accordance with paragraph (b)(6) of this section and § 478.132.